/*******************************************************************************
 * Copyright 2014 United States Government as represented by the
 * Administrator of the National Aeronautics and Space Administration.
 * All Rights Reserved.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/
package gov.nasa.ensemble.core.plan.resources;

import java.util.Collection;
import java.util.Iterator;
import java.util.NoSuchElementException;

import org.eclipse.emf.common.util.TreeIterator;
import org.eclipse.emf.ecore.EAnnotation;
import org.eclipse.emf.ecore.EObject;
import org.eclipse.emf.ecore.util.EcoreUtil;
import org.eclipse.emf.validation.service.AbstractTraversalStrategy;

public class PlanTraversalStrategy extends AbstractTraversalStrategy {

	@Override
	protected int countElements(Collection traversalRoots) {
		int result = 0;
		Iterator<? extends EObject> iter = createIterator(traversalRoots);
		while (iter.hasNext()) {
			result++;
			iter.next();
		}
		return result;
	}

	@Override
	protected Iterator<? extends EObject> createIterator(final Collection traversalRoots) {
		return new Iterator<EObject>() {
			private TreeIterator<? extends EObject> delegate = EcoreUtil.getAllContents(traversalRoots);
			private EObject next;

			@Override
			public boolean hasNext() {
				while (next == null && delegate.hasNext()) {
					next = delegate.next();
					if (next instanceof EAnnotation) {
						next = null;
						delegate.prune();
					}
				}
				if (next == null) {
					// to avoid retaining traversed objects if the iterator is not freed by the EMF validation service
					delegate = null;
				}
				return next != null;
			}

			@Override
			public EObject next() {
				if (!hasNext()) {
					throw new NoSuchElementException();
				}
				EObject result = next;
				next = null;
				return result;
			}

			@Override
			public void remove() {
				throw new UnsupportedOperationException();
			}
		};
	}

}
